Bug ID 472944: SMTPS race condition after STARTTLS may cause incorrect SMTP responses

Last Modified: Sep 13, 2023

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
11.5.1 HF1, 11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.1 HF10, 11.5.1 HF11, 11.5.2 HF1, 11.5.3 HF1, 11.5.3 HF2, 11.5.4 HF1, 11.5.4 HF2, 11.5.4 HF3, 11.5.4 HF4, 11.5.0, 11.5.1, 11.6.0, 11.6.1, 11.6.2, 11.6.3, 11.6.3.1, 11.6.3.2, 11.6.3.3, 11.6.3.4, 11.6.4, 11.6.5, 11.6.5.1, 11.6.5.2, 11.6.5.3, 12.1.0 HF1, 12.1.0 HF2, 12.1.1 HF1, 12.1.1 HF2, 12.1.2 HF1, 12.1.2 HF2

Fixed In:
12.0.0, 11.6.0 HF4, 11.5.2

Opened: Jul 24, 2014

Severity: 3-Major

Related Article: K16312

Symptoms

After STARTTLS handshake, SMTP communication fails due to one of the following reasons: - BIG-IP system responses to SMTP client are not synchronized (that is, the responses do not match the requested commands). - SMTPS profile activation mode is 'require' and the BIG-IP system responds with '530 Must issue a STARTTLS command first.

Impact

SMTP communication using the SMTPS profile might not succeed. intermittently or consistently.

Conditions

This occurs when the following conditions are met: -- A virtual server configured with an SMTPS profile. -- After the STARTTLS handshake on the client side and the BIG-IP system has sent an RSET command to SMTP server, the BIG-IP system receives a command (such as HELO or EHLO) from an SMTP client before the BIG-IP system receives the RSET response from SMTP server.

Workaround

None

Fix Information

SMTP commands received after STARTTLS are now correctly buffered by SMTPS profile until the SMTP server is ready to receive them.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips